DOI: 10.1002/elan.201900163 Nanostructured Gold Microelectrodes for Non-enzymatic Glucose Sensor JanaHovancová, [a] Ivana Šišoláková, [a] PetrVanýsek, [b] RenátaOriňaková,* [a] IvanShepa, [c] MarekVojtko, [c] andAndrejOriňak [a] Abstract: A novel, highly stable, selective, and sensitive non-enzymatic glucose sensor was developed by simple andeffectivemodificationprocedure.Themodificationof gold microelectrodes by electrochemically deposited gold nanoparticles resulted in increase of surface area up to 37%. The nanostructured surfaces of the gold micro- electrodes obtained by different modifications were studiedbyconfocalmicroscopy,atomicforcemicroscopy, and scanning electron microscopy. The gold nanoclusters exhibit great electrocatalytic properties toward glucose withawidelinearrangefrom0.5to50mM,withalimit of detection 218μM, and sensitivity of 185.2mAmM 1 cm 2 .Moreover,themodifiedmicroelectr- odesdisplaygoodreproducibility,stability,andselectivity inthepresenceofpoisoningcompounds.Duetothesmall dimensions of gold microelectrodes and a very small volume of the sample, the microelectrodes make a contributiontominiaturisationofthesystem. Keywords: non-enzymaticsensors · miniaturisation · glucosedetection · nanostructuredgold · goldmicroelectrodes 1 Introduction The development of the glucose sensors has attracted significant attention of researchers because of their application in different fields, such as clinical diagnosis, food monitoring, fuel cells and so on [1,2]. Many techniques were applied for glucose detection, such as optical sensors [3,4], electrochemical sensors [5–8], and colorimetry[9].Amongthem,electrochemicalsensorsare widely used due to their high sensitivity, rapid response, low cost, and portability [10]. Up to date, numerous scientificandreviewpapershavebeenpublishedconcern- ing the glucose sensing, while the majority of articles is focused on clinical detection and the development of an ideal glucose sensor [11–18]. Even though enzymatic sensors are currently widely used in clinical practice and are highly selective due to the specificity of the used enzyme, they display several serious drawbacks. Temper- ature,humidity,toxicchemicals,andpHcouldnoticeably affect the enzyme activity [9]. Moreover, the instability and the denaturation of the enzyme impacts significantly the fabrication process, storage, and the electrode usage [2]. To overcome these disadvantages of the enzymatic sensors, the scientific community makes an effort to develop a non-enzymatic sensor for glucose detection. The objective is to develop a glucose sensor able to provide glucose oxidation directly on the electrode sur- face [17]. Recent advances in nanotechnology strongly influencedthedevelopmentofglucosesensors.Moreover, nanomaterials due to their great catalytic properties originatingfromtheirsizeandshapeareabletoenhance the kinetics of the glucose oxidation reaction [1]. Nano- materials provide a higher surface area and variety of surface modification possibilities, which could improve the electron transfer process and could change the value of the reduction potential of a selected metal. Different types of nanomaterials were used for electrode modifica- tion,suchasnanoparticles,porousparticles,nanospheres, nanocages, and nanoboxes [19]. Various material types were applied for glucose sensors development. Among them transition metals [20–22], metal oxides [7,23], bimetallic systems [24–26] or carbon materials [23,26–28] were intensively studied. The transition metals display favourableproperties,suchasanabilitytoattainmultiple oxidationstates.Moreover,transitionmetalscouldabsorb electroactive species and form intermediates. Application of transition metal nanostructures enhances the mass transport properties, which is important for glucose sensing because of sluggish kinetic of glucose oxidation reaction [29]. Among different transition metal nano- materials, gold nanostructures are the subject of intense research [30]. The main advantage of gold as a substrate forglucosesensingistheabilitytodetectglucoseinboth neutral and alkaline solution. Although the noble metals aremoreexpensive,thetransitionmetals,suchasNi[31], Cu [32], or Co [33] require an alkaline environment because of the catalytic activity of hydroxyl groups. Furthermore, the noble metals display wide linear range, [a]J.Hovancová,I.Šišoláková,R.Oriňaková,A.Oriňak Department of Physical Chemistry, University of P.J. Šafárik inKošice,Moyzesova11,04001Košice,Slovakia E-mail:renata.orinakova@upjs.sk [b]P.Vanýsek Institute of Electrotechnology, Technical University of Brno, Technická10,60200Brno,CzechRepublic [c]I.Shepa,M.Vojtko InstituteofMaterialsResearch,SlovakAcademyofSciences, Watsonova47,04001Košice,Slovakia Full Paper www.electroanalysis.wiley-vch.de © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electroanalysis 2019, 31, 1680 – 1689 1680